A few new seeds were provided by Apple to developers recently, and the seeds include first beta build of OS X 10.9.5 with a label of 13F7. This update is most likely going to be the last one for OSX Mavericks, as we are seeing the highly anticipated OS X Yosemite sometime in October of this year. For those who have signed up to test out pre-release updates, can download the Mavericks seed from the Mac App Store in the Software Update section.

Features that were asked to be focused on in this update include Graphics, Safari, USB, and USB Smart Cards. You can also download the beta from the Developer Center. New seeds of Safari 6.1.6 for OS X 10.7 Lion and OS X 10.8 Mountain Lion 7.0.6 along with Safari 7.0.6 for Mavericks were released by Apple as well. General website compatibility and extensions were asked to be focused upon.

Source: Apple